Cocaine abuse is a growing public health problem in the United States, but existing psychosocial treatment modalities tend to have high relapse rates. Current pharmacological theories of cocaine abuse stress the role of deficient brain dopamine activity and suggest that dopamine agonist treatment might be beneficial. The objective of this study is to evaluate the effectiveness of pharmacotherapy with the dopamine agonist drug bromocriptine. One hundred male cocaine abusers participating in an inpatient (28- day) followed by outpatient psychosocial treatment program will also receive either bromocriptine (7.5 mg daily) or placebo double -blind for the last 2 weeks of hospitalization and the next 6 months and 1, 2, and 3 years after hospital discharge. The major outcome variables will be usage of cocaine and other drugs (including alcohol) and psychosocial functioning assessed using the Addiction Severity Index (ASI). Urine drug screens at each visit will partially validate self-reported drug use. Pretreatment subject characteristics will be assessed for possible predictive markers of treatment response and outcome, including history of other psychiatric disorders (assessed by the Diagnostic Interview Schedule), cocaine withdrawal syndrome (assessed on hospital days 1, 3, 7, and 14). putative brain dopamine activity as reflected in plasma levels of growth hormone and prolactin (measured by visual-analogue sale), treatment participation, and medication compliance will be assessed for their correlation with pretreatment subject characteristics and outcome. Statistical methods used will include repeated measures ANOVA and ANCOVA, Box Jenkins time series, and survival analysis.